Thread-hobbing machine



June 8,1926. 4 1,588,003

' B. H. BLOOD THREAD HOBBING MACHINE Filed Feb. 5, 1920 3 SheetsSheet 1 June 8 1926.

H. BLOOD THREAD HOBBING MACHINE Filed Feb. 5 1920 3 Sheets-Sheet 2 Patented June 8, 1926.

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BRYANT BLOOD, OF HARTFORD, CONNECTICUT, ASSIGNOR TOPRATT & WHITNEY COMPANY, OF NEXT! YORK, Y.', .A CQRPORATION' OE NEW" JERSEY.

THREAD-HOBBING' MACHINE! Application fildiFebruary 5, ;1920; SeriaLNfo; 356,476.-

This invention relates to: improvements in thread hobbing' machines and particu larly to' means. for mounting. the, cutter. spindlein an; improved and novel, manner;

Oneobject: of theinvention is'to providea conical hob and to mount this hob: and

its spindle at such an angle to the Workholder axis that the side of such. hob will engage the work. simultaneously at a; plural.- ity oi: points along a definite line between the hob'and work.

Another object of; the invention is to provide a speciaLformi of tailstock and to mountithe same on thebaseof the, machine directly adjacent the cutter spindle and entirely in front of the cutter spindle pulley or. driving means, such tailstoclt therefore being adapted to. support one end of; the work without interfering with spindle and its driving means;

A further object of. the lnvent ion is to so mount the cutter spindle that. is adapted to be adjusted to different positions and to. operate in, such. positions with. hobbin'gtools of different shapes, whereby the machine may perform the desired work in the most convenient and, efiicient manner. More specifically, the object of theinvent-ion is to provide a. machine adapted toperform a threading operation with either a cylindrical hob or a conical hob, the cutter. beingadaptedtobe adjusted; to different positions to. operate most efficiently on the, Work.

lVith the above and other objects in view which: willappear as the description proceeds, the invention will be described more specifically byreference to the drawings wherein:

Figure: 1 is aside elevation of: a machine embodying. the present inventlom Fig. Qis a plan View of the sa-meshowing a conical hob or cutter mounted: in the-cut ter spindle: and. the spindle in an angular position relative to the workholder; axis,

Fig; 3-is a fragmentary; detail view showingthe cutter spindle in one otits operative positioiistparallell to the; workholderaxis."

4 is a like view showingthe cutter spindle in another. position. c Fig. 5' ise' detailsectional vie-w takenon the line 5.-5-of Fig, 6:.

, Ed .1 v6 is: a" detail sectional view talzenion the cutter Fig; 7@is;a detail sectional{viej taken, on the-line 7-7 of-Fig; 6. I

Referring, more especially to the draw.-; ings by reference characters,f1. indicates the base or bed of the machine orrwhich is mountedga headstockfl proxjrli'dedrwith a r.o,-, tatable; Worlc spindle Tlhelworlg, may he supported and-v driven, solely by, meansot 1 a suitable; chuck 4: carriedby the spindle on it may; be supported; in partjby, the chuck orspindle andinpart by a center, mountedon a s-uitable tailstock.5.. Trhework spindle 3 is; adaptechtobe driven from ainain-driviing 1 shaft. 6. through azny suitablepower, con.- nections such as those illustrated. dotted lines in Figs. 1 and 2. The machine-is provided with a; cutter spindle 7 which is adapted to carry a. thread; cutting hob,hav-' ing longitudinally spaced outtingteethconl formingto the thread a to be out. 'Ehe hob may. be either of-the cylindr ical type-or. the

conicali type,, as; illustrated; in the drawing, the part culan type usedjdepen'ding on: the

shape of the work to be out and'on the-angur lar' position of the cuttenspindle, Preterably the cutter spindle 7. is c'arnied, by I a carriage 8, which is longitudinally adjust lab(l1e-1or. movable along suitable ways: on i the Suitable mechanism is; provided} whereby the hob spindle 7 .isoperated or fedin-synchronism with the rotation,- of the: work spindle- 3 in such a manner as aroma correctscrewthreads, While I- do-notso limit myself-, I prefer to; provideandhave illus trated a hob having; annular rows of cutting teeth. and i when such ahob is j provided:v the a feeding"longitudinally offthe work axis in timed lrelationqwith the; rotation, of. the worlt spindle. In, this case the, cutter spindle may; bejrotated at any oonyenient or suitable, speed ,tosecure: e flieient cutting. As

means 5 S -t le ar ieee i r e a a handle 11" adaptedto; ope a-te' a. nut 11 ro tat-ablythreadedlon thelead; screw 9 and tata ab nmeaatea in. As;

' synchronous operation takes the formofd this invention to provide means for supporting the cutter spindlein dilferent relative positions whereby the particular operation to be performed may be done with the maximum ease and ellicie'ncy. To this end, the transverse slide 13 movable on its support by means of a hand wheel 1 1 is adapted to support a frame 15 thereon in different relative positions. The cutter spindle is mounted on this frame adjacent the work holder and carries a driving means, as the pulley'16, at its outer end. Belt-tightening and guiding pulleys 17 are mounted in line with the pulley 16 on a bracket 18 secured to the frame by screws or otherwise. These pulleys may be adjusted to the proper belttightening position by means of the thumb nut 19. The frame may be secured on its support by any proper means, as by tap bolts 20, 20 and 20 adapted to be threaded into any one of a series of tapped holes 21, 21 and 21"; 21, 22 and 22; or 23, 23" and 23 In Figs. '1 and 3, I have shown the frame as mounted in the first position with the securing tap bolts engaged in holes 21, 21 and 21*. In this position the cutter spindle is parallel with the work spindle and adapt ed to operate on the work W with a cylindrical hob 241. This position of the spindle is use-d in operation on short chuck work or work secured entirely within the chuck l without the aid of the tail'stock. As illustrated in Figs. 1 and 3, the tailstock 5, not being used in thisoperation, is drawn back to its extreme rearward position on the bed;

lVhen performing a threading operation on cylindricalwork by means of a cylindical hob or cutter it is necessary t iat the cutter spindle axis be parallel with the rotary axis of the work. When operating on relatively long work between the ends there of or adjacent the headstock 2, such work being supported between the headstock and tailstock, the difficulty of properlysupporting and operating the cutter spindle so close to the work and tailstock is presented. To

avoid this diliiculty I have herein substituted aconical hob 25 for the cylindrical hob,

which construction permits and necessitates an angular-arrangement of the cutter spindle relative to the rotary axis of the work. In such construction, the cutter is mounted on the end of the cutter spindle adjacent the work, and the driving means, as the pulley 16, is mounted on the end of the spindle spaced from the work and opposite the tailstock as shown in Fig. 2, such spacing of the spindle providing sulficient space for the with a conical hob 25 which is adapted to engage the work l/V simultaneously at a plu rality of points along a definite line between the axes of the hob and work. In this posi-. tion the cutter spindle is arranged withits longitudinal axis .at an angle to the axis of the work holder and when using a true conical hob, such as illustrated in Fig. 2, the axes of the cutter spindleand the work holderare in a common plane. It should further be noted that the angle between the cutter spindle axis and the work holder axis conforms to the sum of the angles formed between the line of engagementof the hob and work and the respective axes thereot.

Fig. 1 illustrates another position of the cutter spindle and its relation to the tailstock and other parts of the machine when operating on the tailstock end of work supported by both the headstock and tailstock. The frame 15 is herein shown as secured by the tap bolts engaging inholes 28, 23 and 23. This position of the cutter spindle is like that illustrated in Fig. 3 except that the cutter is in a different longi tudinal position on theslide 13. The tailstock is made of the special form illustrated for the purpose of supporting the work IV in axial alinement with the headstock spindle and at the same time of fitting closely adjacent the cutter spindle. The operat- .ing handles of the tailstock project directly away from the cutter spindle and the pulley 16 is adapted to extend beyond and overlap the tailstook. Such construction permits firm support of the work at both ends, support of the cutter spindle parallel to the work axis and at the same time provides suiiicient space for the pulley 16 or other operating means for the cutter spindle.

It should be noted that in securing the positions illustrated in Figs. 2 and S, the frame 15 is swung about the bolt 20 which acts'as a pivot remote from the work holder axis. Because of the remoteness of this pivot the location of the cutter in'these two fill adjustments-areiquite widely" separated. It

should furth'er be noted' that in the two ad'- just'inents illustrated Figs: 2 and ithe cutters are approximately in the s'a'me' locatiorr hi es-e11 adj u'stinent; the parallel adjustment oftli'e' spindle shown in Fig. 4 ho'wever adaptin'gthe machine to operate'witha cylindrical hob on cylindrical Work and the V angular.adjustnient shown in Fig; 2 adapting the machine tem erateeither on cylindri'c'a'l'work witha conicalhob or with-a cylindrical hob on conical worki lVhenmilling screwthreadsit is very es- A sential that'tlie hob-be' in a definiteangular position relative t'othe work holdera'xis. This o tio'nij this means being 'illustiated?specific ally- 2 female taperthreads adjustment mustbe 'very: fine'and accurate and-fa'ccordingly I have designed a special adj ust-ingmeans for performing-l this funcin Figs."5; 6 and *7l The hole in frame 15 through which'the ta'p bolt 2O passes 6') "is-'provided with a circular outer portion 26 (Fig. 7) and an o'val in'n'er portion 27 An eccentric'busliing' 28 surrounds thebolt': 20 and extends entirely through tliehole QG; 2'7. The shorter axis a b" (Fig: 5 of uieovzu hole 27 extends in a" direction parallel to the cutter spindle I axis" and the eccentric, bushing 28' engages 'ohljth'e shorter diameter sides otthishol'e. Itwill theret'orebeseen that" by rotationotthe bushing 28 the trains 15 is adjusted about the pivot bolt 20 as a center and'the cutter is adjusted angularly to the work- 'spindle axis Also the adjusting pressure of the bushing tafke splace' only in' the hole portion 27 directly adjacent the supporting slide 13; Theope'ningrin' frame 15 through which the" bolt 2O extends isoversizesuffi cie'n' t-lj to" allow the slight adjustment defined. Aittert properly adjusting the frame,- the three boltsQO, 20-, and QO 'a're securely the fralne rigid: Vol-qr ing position;

liile in" the work and in the" specification I have generally described such anroperation, it should be clearly understood that the invention is not liniited thereto since the machine is ad apt'e'd to operate either on internalor externalwork of cylin'di'i.cal or conical" form, such foreizalnple' in determining the; scope" of the intention.

hat I" claln'i 1s:

1 In a screw" holderinount ed therein, a'tailstock in axial alignment was the" work holder' 'a cutter at an angle spindle supported with its axis 1 t.

drawing I? have shown the cutter asoperating on external cylindrical hobbing' either male orf' on pipe couplings with: v either cylindrical or'conical' hobs. 7 Reference to theappended claims should be made thread milling machine, the combination of a headstock, rotary work re axes or a vcoinn'ion plane", a conical threading? hobmounted on'th'e end o l the cutter spindle adjacent the work holder axisandadapted to engage" the work simultaneously at a pluralit' -of Joints alone adefinite line between the axes of the hob and work, a drive wheel mounted onthe end of the spindle, the angular mounting oct'the cutter spindlebe in'g adapted to space the drive wheel: {real the axis otthe work] holder and the tailstock, and means operatii'iely connectir' the n-orlt' holder withithe cutter spindle where by-the latter is operated synchronously with the rotation of the former.

2. In a-ni-illin'g machine, the combination of a headstock; a rotary work holder mounted therein, a tai stock in axial; alignment, with the-"work holder,- a cutter'ca'rriage a" cutter spindlesupported on the carriage directly adjacent and parallel with the work holder axis and the tailstock, and a pulley supported on the rear end of the: cutter spindle andinovable with the carriage, such pulley; being positioned to the-rear of and projecting over the end of-the tails'toclt;

3; In ascrew" thread millingimachin the I combination off a=rotary"work holder, a tailstock in axial" alignment with the work holder,- a cutter CZIT'llEl-gfi, a'cutter spindle supported on the carriage directly adjacent and parallel with the work holder axis andthe tailstock, end oi' t-he cutter spindle and'jinovable with the carriage such: pulley being positioned to therear of: and: projecting over the end o'f'the" tailstoclr, and i means operatively connecting the work holder with the cutter spindle whereby the'latter isfoperated syn chronously" with the rotation of the former.

4; In' a screw tln'eadmilling machine the combination 5 of a rotary work holder, a carriageadjustable longitudinally of the work holder axis, a tailstock inxaxi'al'alignment' with:theworkholdeiga cutter spindle supported on the carriage directlyadj scent and parallel with the work holder, axis and'the tailstock', a pulley supported onthe rear end o'f the cutter spindle and movable with thecarr'iage, such pulley being-Epositionedto the rear of and projecting overthe end of the a pulley Supported onth'e'rear tailstoclr, and means operatively connecting" I the work holder with the carriage whereby thelatteris fed longitudinally oil the wor-lr frame, such. pulley beingv positioned to the neat oi-+- andi projecting; over tlre end of; the:

ill

tailstock, and'means for slightly adjusting the frame to adjust the hob angularly of the work holder axis.

In milling machine, the combination of a headstock, a rotary work holder mounted therein, a tailstock in axial alignment with the work holder, a cutter spindle, apivoted frame for supporting the cutter spindle directly adjacent and parallel with the tailstock, a pulley supported on the rear end of the cutter spindle and movable with the frame, such pulley being positioned to the rear of and projecting over the end of the tailstock, and means for slightly adjusting the frame about its pivot to adjust the hob angularly of the work holder axis.

7. In a screw thread milling machine, thecombination of a rotary work holder, a cutter spindle, a threading hob mounted on the cutter spindle and adapted to engage the work.

simultaneously at a plurality of points along a definite line between the hob and work, a frame for mounting the spindle, a support, means for securing the frame to the support in any one of a plurality of fixed predetermined working positions, the axes of the work holder and spindle being in a common plane in all such positions, and means operatively connecting the work holder with the cutter spindle whereby the latter is operated synchronously with the rotation of the former. I

8. In a screw thread milling machine, the combination of a rotary work holder, a cutter spindle, a threading hob mounted on the cutter spindle and adapted to engage the work simultaneously at a plurality of points along a definite line between the hob and work, spindle-si'ipporting means comprising a frame adapted to operatively support the spindle in a position parallel to the rotary axis of the work holder or at an angle thereto, the of the work holder and spindle being in a common plane in all suchpositions, means for rotating the spindle in either of such positions, and means operatively connecting the work holder with the cutter spindle whereby the latter is operated synchronously with the rotation of the former.

9. In a screw thread milling machine, the combination of a rotary Work holder, a cutter spindle, a threading hob mounted on the cutter spindle and adapted to engage the work simultaneously at a plurality of points along a definite line between the hob and work, a support, spindlesupporting means comprising a frame pivoted to the support and adapted to be adjusted about its pivotto operatively hold the spindle in a position parallel to the rotary axis of the Work holder or at an angle thereto, the axes of the workholder and spindle being in a common plane in all such po'sitions,'1neans for rotating the spindle in either of such positions,

and means operatively connecting the work holder with the cutter spindle whereby the latter is operated synchronously with the ro tation of the former.

10. In a screw thread milling machine, thecombination of a rotary work holder, a cutter spindle, asupport, spindle-supporting means comprising a frame pivoted to the support on a pivot remote from the work holderaxis, the frame being adapted to be adjusted about the pivot to operatively hold the spindle in a position parallel to therotary axis of the work holder with the cutter in one position and location or at an angle thereto and withv the cutter in another position and location, the axes of the work holder and spindle being in a common plane in all such positions, means for rotating the spindle in either of a such positions, and

means operatively connecting the work holder with the cutter spindle wherebythe latter is operated synchronously with the r0- tation of the former.

11. In a screw thread milling machine, the combination of a headstock, a rotary work holder mounted therein, a tailstock in axial alignment with the work holder, a cutter spindle, spindlesupporting means comprising a frame adapted to operatively support the spindle in a position parallel to the row tary axis of the work holder or at an angle thereto, a pulley supported on oneend of the cutter spindle and spaced to one side of the work holder axis and opposite the tailstook when the cutter spindle is in the angular position, and means operatively connecting the work holder with the cutter spindle whereby the latter is operated synchrowhen the cutter spindle is in the angular position, means for varying the relative angular position of the cutter splndle by adusting the spindle support in a manner to move the pulley substantially. directly to wardor away from the work holder axis, and means opera-tively connecting the work holder with the cutter spindle whereby the latter is operated synchronously,with the rotation of the former.

13. In a screw thread milling machine,-

the combination of a rotary work holder, a spindle-supportlng frame, a cutter spindle mounted therein and adapted tooperatlvely receive-either a, cylindrical Ora conical hob,

means. forsupporting the frame with the cuta former.

two}. posi 'ter, s'pin -;lle parallel with the work holder axis when o'peratingwi'ththe cylindricalhob and at an angle thereto when operatingwith the, conical hob, eachho b heing.adapted to engage the work siinul'tan'eoiisly atla'plurality of points along ajdeiinitefline'between the. hob and work andlthe r axes got the hob and work being a con mon plane,' and means connecting the work, holder with the cutter spindle whereby I the latter is oper 'eted synchronously with the rotation 'ot the 14,1111 3 s e ;thre dw ll n m chi the combination of'a rotary work holder,-

1ng adjustable'ahout its' pivotito {secure the,

ions, each hob being adaptec to engage the work,simultaneously'et aplu- 'a1 y fPQin %alQns aid fi i e l ne tw ,the hob and "worksandthe axes of the hob;

a ewb ing n. Q m n, v a means t-eonnecting the "work holder with. the

- of the frame: to different; positions togopera- 5 tively hold the spindlein-al position -pa-rallel; to; the rotary axis of, the; work holder or, at

outter,spindle'whereby the latter is operated synchronously with the rotation of.-.the= forner; 1

' 15,111 a screw thread -millingwinaohine, the oomloinationof a rotary work: holder, a rc t spin a upp rt; spinc 'l esepp I j means comprising Y frame inountedjon the support, means vpermitting adjustmfi nt an angle thereto,- auxili ary'means; ior slightlynadjusting the iranieangularlyof the work v holder ems-after the frame 11 as -been set to working pOS1tlO1'1,;2LIlCl means opera-trvely connecting'the work holderwith the cutter v spindle,- whereby the: latten is operated: syn-H chron ouslyj withjthe rotation-(of the former.

, 16; a screw thread milling machine, the combination 01E aurotary work; holder a-cutter spindle, a frame for supporting the spindle, a carriage adjustable longitudinal- ,ly-of the workholder axis; means for securthe frame toithe carriage inany one ofa plurality of fixed,predetermined working positions, the I axes-f the, workihol der and spindle being in a ooin non plane in all-such =positionS,Z"aI1d means operatively CO1 1I1eCl2iIlg the work holder with the carriage 1 whereby the carriage-1s moved long tud nallyaof the 7 [work holder taxis insynohronisni with-the rotation "of the former.

1 In qr w-=- rea l the combination oiaa rotaryjgwor1; holder, a

;; cutter spindle, spindle-supponting 5 ;n1eans Lv rotation of theYforIner.

colnprisinga frame adapted, to headjusted to operatively support the; spindle in aposition; arallel to the axis of the work "holder or at an angle thereto, the .axes of the work "holder and. spindle .being in"v a common plane in all such'ipositions the cutter beingiin ap o proximately the.samelocationin loothadusted positions of; the frame, means for .ro- ,tating the spindle in eithertof. "such positions,

and means operatively connecting the work.

vholder with the cutter spindle whereby the latter is operated, synchronously};with the 418. In a sore v eh admniin ;m ttingthe ,o01nhination or a headstock, a rotarygwork iliolderi inounted therein, atailstock ingagiial V alignment with 1 the, work lei, a o u tter spindle, spindle-s11pportin' ans, eqinpris- .nig a ira ne gadapted to be, .ad steel, t operparallel to: the axis er. the lwork hold-en it at 33,11 angle .tliereto, the i ei aeg teingj inzappro'xim'atelyi the senile location in both adji sted positions offlthe' irai'ne, ,a Julley :,supported "dgsp a eed' .0 1 1 91 1; Lth ep idlat ,to one sideof the work, holder ,airislandiiopposite the .tailstoob whengthe 'outter spindle is inlthe angular posit" n andibeingvposr ti e the? e the; end of ,the tailstock when, the; cn-tter spindle is the parallel, position and ineans operatiyely conneotinglthe w orli holdei {with 1 the cutter.spindlewhereby thelatterl is per- A ted, synchronously, with the: rotation oif the fo'riner. V f d i j I vs19. -In a; screw 1 thread; grnillling 1 .inaohine, :the com nat w a heedstb rotary work holder mounted. I

' l et d the a ded mali qiiea-tive y rece ve either a oylindlf pi li 01' a, oon oal hob,

f; means for, supporting the liraineniwith nthe V cutter l spindle 'p arallel to (the work holder axis, .w-hen (operating with the eyli nd hoband at an angle thereto with thegconic al hob, the}! justnients of, the frame, a} pulleyfinioiinted ,on onej endfoftoone side-of positef the tailsto cl;

the gutter! is indle is in the angular posit on and being ,posi- .i tioned to the rear oliancl proj eeting over the I ond o' fthe tailstook when the gutterspindle:

is injthegparallel, position, nd means reperativelyiconneotingthe gsvo-rk h qldriwith the cutter gspindleIwher ehy it heilatter is operated former.

' O. *In a; screw thread? 1n il lin'g,- niaohine,

-;Om ihati s- 'e'irot oweiklh d s ie et ere .spmdleeeplaellezsan rtms i iva ee s emnr e s Mena ,aden d taer v y ca.suppe t-Ythasi ie l a n a pqi t oeipa-w ri'cal utter. spindle} and spaeed work llQldGiQilXlS n clop- I y e p s y wi ptetie i ei i h 0., H ,iv..-capproximately the saine locat on .in hoth adi the rotary axis of the work holder or at an frame thereon in any one of a plurality of definite working positions along the axis of the work holder, and means operatively connecting the. work holder with the cutter spindle whereby the latter is operated synchronously with the rotation of the former.

22. In a screw thread milling machine, the combination of a rotary work holder, a cutter spindle, a frame for supporting the spindle, a support provided with means for holding the frame thereon in a relatively forward position with the cutteradjusted to operate closely adjacent the work holder or in another position on the support rearwardly of the first mentioned position, a pulleyv mounted on one end of the cutter spindle and positioned to the rear of and projecting over the end of the tailstock when the cutter spindle is in the last named position, and means operatively connecting the work holder, with the cutter spindle whereby the latter is operated synchronously with the rotation of the former.

' 23. In a screw thread milling machine, the combination of a bed, a rotary work holder thereon, a cutter spindle, a frame for supporting the spindle, a cutter carriage movable longitudinally on the bed and provided with means for holding the frame thereon in any one of a plurality of definite working positions along the axis of the work holder,

means for slightly adjusting the frame angularly of the work holder axis after the frame has been set to working position, and

means operatively connecting the work holder with the cutter spindle whereby the latter is operated synchronously with the rotation of the former.

24. In a screw thread milling machine, the combination of a bed, a rotary work holder thereon, a cutter spindle, a frame for supporting the spindle with its axis parallel to the axis of the work holder, a cutter carriage movable longitudinally on the bed and provided with means for holding the frame thereon in anyone of a plurality of definite working positions along the axis of the work holder, the rotary axis of the cutter spindle being parallel to the rotary axis of the work holder in all positions of adjustment of the maths frame, and means operatively connecting the work holder with the cutter spindle whereby the latter is operated synchronously with the rotation of the former.

In a screw thread milling machine, the combination of a bed, a rotary work holder thereon, a cutter spindle, a frame for supporting the spindle,- a cutter carriage longitudinally movable on the bed, means for securing the frame to the carriage in three fixed predetermined working positions, and means operatively connecting the work holder with the cutter spindle whereby the latter is operated synchronously with the rotation of the former.

26. In a screw thread milling machine, the combination of a bed, a rotary work holder thereon, a cutter spindle, a frame for supbodily moved on the support to different working positions and secured insuchadjusted positions, and means connecting the work holder with the cutter spindle whereby the latter is operated synchronously with the rotation of the former.

28. Ina screw thread milling machine, the combination of a rotary work holder, 2, cutter spindle, a support, spindle supp'ortingmeans comprising a frame pivotally mounted on the support, such support having means whereby the frame may be adjusted about its pivot or bodily moved on the sup port to different working positions and secured in such adjusted positions, and means connecting the work holder with the cutter spindle whereby the latter is operated synchronously with the rotation of the former.

29. In a screwthread milling machine, the combination of a rotary work holder, a cutter spindle, a carriage adjustable longitudinally of the work'holder axis, spindle-sup-I porting means comprising a frame mounted on the carriage, the carriage'having means whereby the frame may beadjusted angularly or bodily moved thereon to dififerent working positions and secured in such adjusted positions, and means connecting the work holder with the cutter spindle whereby the latter is operatedsynchronously with the rotation of the former. Y I

- 30. In a screw thread milling machine, the

1,588,003 l I i I '7 combination of a rotary Work holder, a cutjusted positions, and means operatively conter spindle, a carriage adjustable longitudi necting the Work holder with the carriage 10 nally of the Work holder axis, spindle-supwhereby the latter is fed longitudinally of. porting means comprising a frame mounted the work holder axis synchronously with the on the carriage, the carriage having means rotation of the former.

whereby the frame may be adjusted a-ngu- In testimony whereof, I hereto aflix my I larly or bodily moved thereon to diflierent Signature.

Working positions and secured in such mt BRYANT H. BLOOD. 

